The cell phone towers dotting the nation's landscape carry more than phone signals. They can track locations by following the silent pulses phones emit. "'Pings' are another word for cell phone signals that your cell phone gives off constantly," said Minn. Rep. Sheldon Johnson (DFL-St. Paul).

Johnson wants to require cell phone companies to let police follow the pings when a person goes missing. "You'll have a better chance, definitely, the sooner that law enforcement can contact you," he added. The bill comes two years after Kansas teenager Kelsey Smith was abducted from a parking lot. Her parents said their wireless carrier resisted efforts to release their daughter's cell phone location.

When they did get it four days later, they found Kelsey's body within 45 minutes.